The conventional multiple speed bicycle employs derailleurs to manually move the drive chain from one size diameter sprocket to another size diameter sprocket, either on the drive sprockets or the sprockets on the driven wheel. The objective of this system is to progressively change the gear ratio to match the speed of the vehicle as it increases. Whenever such a system is used on bicycles, it improves the efficiency of the pumping of the pedals. In order to accomplish this task, the rider starts in the low gear ratio with the drive chain on the smallest driver sprocket and on the largest driven sprocket. As speed is increased, the gear is changed to the next highest gear by manually changing the driven gear via the derailleur mechanism. The next highest gear ratio is obtained by changing the driver sprocket from the smaller to the larger. The next highest gear ratio is obtained by first lowering the driver sprocket and also increasing the driven sprocket to the next size gear. The next highest gear ratio is obtained by changing the driver sprocket back to the larger. The next highest gear ratio is obtained by changing the driver sprocket from the larger to the smaller and also increasing the driven sprocket to the next size gear. In the case of a ten-speed bicycle, this process continues in the above described pattern until the tenth gear ratio is obtained. To obtain a smooth operation when the speed decreases, the above process has to be reversed.
It is an object of the present invention to provide an automatic transmission system for a cycle which automatically changes the gear ratio as the speed of the bicycle increases or decreases.
It is a further object of the present invention to provide an automatic transmission system for a bicycle which has continuously variable gear ratios.
It is a further object of the present invention to provide an automatic transmission system for a bicycle that improves the efficiency of pedalling.
It is still another object of the present invention to provide an automatic transmission system for a bicycle which is relatively inexpensive, easy to use, and easy to implement.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.